1. Field of the Invention
The present invention relates to a stamp unit including a stamp body, an ink impregnated body fitted in the stamp body, and a stencil sheet formed with a stencil image and covering the ink impregnated body.
2. Description of Related Art
There has been proposed a stamp unit including a stamp body, an ink impregnated body fitted in the stamp body, and a thermal stencil sheet covering the ink impregnated body. The stencil sheet is formed with a stencil image. By pressing the ink impregnated body covered with the stencil sheet against a print medium to be printed on, an ink image corresponding to the stencil image is formed on the print medium.
Japanese Patent-Application Publication (Kokai) No. HEI-9-99618 has proposed a stamp unit 100 shown in FIGS. 1 to 4. The stamp unit 100 enables a stencil sheet to be easily attached to a stamp body, and also prevents ink leaks.
Specifically, as shown in FIG. 1, the stamp unit 100 includes a stamp body 101, an ink impregnated body 103, a stencil sheet S, and a skirt member 105. The stamp body 101 is formed in a rectangular parallelepiped shape, and has a grip portion 102. The ink impregnated body 103 is attached to a lower portion of the stamp body 101, and is impregnated with ink. The stencil sheet S is formed with a stencil image. The skirt member 105 is detachably fitted to the stamp body 103.
The skirt member 105 is formed in a rectangular frame shape with an inwardly extending lip portion 113 defining an opening portion 106 at its lower surface. The skirt member 105 has a pair of first inner wall surfaces 107 opposing each other and another pair of second inner wall surfaces 108 opposing each other. A first guide portion 109 is provided to each first inner wall surface 107 so as to protrude from the first inner wall surface 107 to an inner edge of the lip portion 113. A second guide portion 111 is provided to each inner wall surface 108 so as to protrude from the inner wall surface 108 to an inner edge of the lip portion 113. The first guide portion 109 and the second guide portion 111 have a top surface 110 and a top surface 112, respectively, to receive and guide the stencil sheet S and the stamp body 101 to which the ink impregnated body 103 is attached. As shown in FIG. 2, an escape portion 114 is formed to each of four internal corners of the skirt member 105 between the first guide portions 109 and the second guide portions 111.
Next, operations for mounting the stencil sheet S to the stamp body 101 will be described. First, the skirt member 105 is fitted to an outer periphery of the stamp body 101 from below while the stencil sheet S clings by viscosity of the ink to a lower surf ace of the ink impregnated body 103. Then, the slanting guide surfaces 110 of the first guide portions 109 guide corresponding lengthwise edge portions of the stencil sheet S into intimate contact with corresponding sides of the stamp body 101. Next, the slanting guide surfaces 112 of the second guide portions 111 guide widthwise edge portions of the stencil sheet S into intimate contact with corresponding sides of the stamp body 101. Corner portions 115 of the stencil sheet S shown in FIG. 3 enter the escape portions 114 as guided by the first and second guide portions 109, 111.
In this way, the stencil sheet S can be easily and reliably mounted to the ink impregnated body 103 without the stencil sheet S peeling away from the ink impregnated body 103.
However, ink may leak out from the corner portions 115 of the stencil sheet S when the stamp unit 100 is laid on its side. Specifically, although the lengthwise edge portions and the widthwise edge portions of the stencil sheet S are in the intimate contact with corresponding sides of the stamp body 101, the corner portions 115 are not, so that the corner portions 115 are open. Ink can leak out through the openings C in the corner portions 115.
Also, as shown in FIG. 4, an upper portion of the skirt member 105 is not in contact with the stamp body 101 so that a space 116 is formed between the upper part of the skirt member 105 and the stamp body 101. The space 116 exposes the escape portions 114, that is, the opening portions of the corner portions 115, so that ink from the corner portions 115 can leak out through the space 116.
Therefore, when the stamp unit 100 with a large amount of ink impregnated in the ink impregnated body 103 is laid on its side, the ink may flow from the ink impregnated body 103 through the corner portions 115 and the space 116 to the outside of the stamp unit 100.
This problem will not happen as long as the stamp unit 100 is handled while kept in an upright posture. However, it is inconvenient and difficult for a user to handle the stamp unit 100 in such a restricted manner.